The present invention is directed to a catch mechanism for releasably connecting a head part to a gripping part of a dental handpiece. The head part contains a head housing with a neck part terminating in a shank which is received in a guide sleeve of the gripping part and the shank and guide sleeve are provided with anti-twist elements to prevent rotation therebetween. The catch mechanism will include at least one catch element have a radially acting engageable element which is carried by one of the two parts and cooperates with a stop face on the other of the two parts to form a latching connection between the two parts while assembled and the mechanism includes an actuation element for disengaging the catch element from the stop face to enable disassembly.
A radially actuated catch mechanism is disclosed in U.S. Pat. No. 4,348,180 whose disclosure is incorporated by reference thereto and which patent claimed priority from a European application which issued as European Pat. No. 0,029,862. As disclosed in this patent, the neck part of the head part contains a spring-elastic annular sleeve which forms a surface of the handpiece in this region and terminates flush with the surface of the neighboring handpiece parts. Located in a lateral surface region, which is tangential with the head housing, are webs or ridge members which extend parallel to the axis of the annular sleeve and on whose free ends are outwardly directed catch noses or elements which are designed to move radially inwardly and outwardly to engage corresponding recesses in a gripping sleeve. The latch connection can be released in that the head part is grasped with the thumb and index finger in the region of the side edges of the neck part, for example, preferably in the region which is practically tangential with the head housing and are pressed against the annular sleeve. As a result of a deformation of the annular sleeve produced in this way, the catch noses will be disengaged from the locking recesses in the grip part.
In terms of surface, this arrangement of the elastic annular sleeve as well as the webs connected thereto to extend parallel to the axis and having the catch noses, takes a comparably great amount of space. Added thereto is that the sleeve acting as an actuation member forms a relatively large visual surface which must be executed in accordance with the remaining handpiece surface and is, thus, relatively cost intensive.